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Conjugated polymers with high charge mobilities have drawn increasing attention in organic field-effect transistors (OFETs) in recent years. However, OFETs of conjugated polymers with high mobility and good device stability remain a challenge. In this article, we report a hyperbranched polymer approach to improve the charge mobility and device stability. Three hyperbranched diketopyrrolopyrrole-based polymers were designed and synthesized via linear alkyl side-chain linkers. The results show that 2D topological hyperbranched polymers form stable thin film microstructures, and thus improve the device stability, since the conjugated moiety is interconnected by linear alkyl chain. Besides, the incorporation of linear alkyl chain instead of branching alkyl one reduce steric hindrance, and improve the microstructure ordering as well as the charge mobility. Bar-coated OFETs result demonstrates that the devices mobilities and operational stabilities (bias stability and bending resistance) are both improved. All these indicate that hyperbranched polymer is a potential candidate for future application.

Graphene nanoribbons (GNRs) are promising in organic optoelectronic materials, and their properties largely depend on the size, edge, and conformation. Herein, the fully armchair-edged GNRs (AGNRs) with lengths up to 2.65 nm by using a Cu-catalyzed deoxygenative coupling as a key step. The resulting AGNRs (2HBT, 3HBT, and 4HBT) possess highly twisted π-scaffolds, and the torsion angles between the adjacent triphenylene moieties are larger than 32°, as proved by crystallographic analyses. Theoretical and spectroscopic studies show that the butoxy groups endow AGNRs with electron-rich features, the extension of the π-system from 2HBT to 4HBT reinforces S

Baeyer–Villiger (BV) oxidation is a fundamental organic reaction, whereas the hetero-BV oxidation is uncharted. Herein, a tellura-BV oxidation is discovered. By oxidizing a tellurophene-embedded and electron-rich polycycle (1) with mCPBA or Oxone, an oxygen atom is inserted into the Te–C bond of the tellurophene to form tellurinate lactone mono-2. This reaction proceeds as follows: (i) 1 is oxidized to the tellurophene Te-oxide form (IM-1); (ii) IM-1 undergoes tellura-BV oxidation to give mono-2. Moreover, the hybrid trichalcogenasumanenes 7 and 8 are, respectively, converted to tellurinate lactones mono-9 and mono-10 under the same conditions, indicating that tellura-BV oxidation shows high chemoselectivity. Due to the strong secondary bonding interactions between the Te Created by potrace 1.16, written by Peter Selinger 2001-2019 O groups on tellurinate lactones, mono-2, mono-9, and mono-10 are dimerized to form U-shaped polycycles 2, 9, and 10, respectively. Notably, mono-2, mono-9, mono-10, and their dimers show chirality. This work enables one-step transformation of tellurophene into tellurinate lactone and construction of intricate polycycles., A tellura-Baeyer–Villiger oxidation is discovered, which enables one-step transformation of tellurophene into chiral tellurinate lactones. The resulting tellurinate lactones are dimerized in the solid state to form U-shaped polycycles.

Buckybowls have concave and convex surfaces with distinct π-electron cloud distribution, and consequently they show unique structural and electronic features as compared to planar aromatic polycycles. Doping the π-framework of buckybowls with heteroatoms is an efficient scheme to tailor inherent properties, because the nature of heteroatoms plays a pivotal role in the structural and electronic characteristics of the resulting hetera-buckybowls. The design, synthesis, and derivatization of hetera-buckybowls open an avenue for obtaining fascinating organic entities not only of fundamental importance but also of promising applications in optoelectronics. In this review, we summarize the advances in hetera-buckybowl chemistry, particularly the synthetic strategies toward these scaffolds.

Hetero-buckybowl trichalcogenasumanenes (TCSs, 1/2) are electron rich and feature oxidative reactions. Herein, the compounds 1/2 are selectively oxidized by nitric oxide species to afford diverse products. In the presence of tert-butyl nitrite (condition a), two flanking benzene rings on trithia-(1)/triselena-(2) sumanene are oxidized to give 3/4, where one ring is opened and the other is converted to ortho-quinone. When NaNO2-TFA is the oxidant (condition b), compounds 1/2 are transformed into 5/6 with one flanking benzene opened while the other two flanking benzenes are oxidized to ortho-quinones. It is found that the butoxy groups on the diimide species 7/8 derived from 1/2 are transformed into ortho-quinones to give 9/10 under condition b. Taking these reactions as a key step, various electron-deficient polycycles, 16–21, which possess imide and pyrazine moieties, are created. Compounds 3–6 and 9/10 show electrochromism due to the existence of the ortho-quinone moiety. The LUMO energies of compounds 18–21 are comparable to the n-type organic semiconductor perylene diimide, and compounds 18–21 can serve as electron acceptors to form complexes with electron-rich polycyles.

Nonvolatile memory devices based on organic materials are promising for a new generation of portable or flexible electronics. Herein, two pyrene-fused azaindacene configurational isomers, syn-B2IPIO and anti-B2IPIO, were designed and synthesized, and they are axially symmetric and centrally symmetric, respectively. These two regioisomers were applied as charge trapping elements (CTEs) for the electret layers in organic field-effect transistor nonvolatile memory (OFET-NVM) devices. Although the two regioisomers have nearly identical molecular structures, absorption spectra, and HOMO/LUMO energy levels, they exhibit distinctly different charge-trapping capabilities. The OFET-NVM devices based on anti-B2IPIO exhibit a moderate memory window of about 25 V. In contrast, the devices based on syn-B2IPIO show a more than two-fold wider memory window (∼59 V). The different charge trapping behaviors of this pair of isomers are attributed to different intermolecular interactions associated with molecular symmetry, resulting in different molecular packing behaviors and film morphologies. The results reveal that controlling the molecular symmetry could be a new and efficient strategy for the design of organic CTEs for high-performance memory devices.

Magnetic molecular materials with a chiral configuration are attractive candidates for sensing, information storage, and spintronics. Herein, we report the first example of two-dimensional hybrid p...

The electron donor tetrathiafulvalene (D 1 ) was fused onto the electron-rich heterabuckybowl trichalcogenasumanene (D 2 ) through an electron-deficient pyrazine unit (A) to give 1 c, 1 d, 2 c, and 2 d, featuring the D 1 –A–D 2 structure. Both D 1 and D 2 play a pivotal role in intramolecular charge-transfer (ICT) transitions, consequently 1 c, 2 d, 2 c, and 2 d show a broad ICT band at 450–720 nm in steady state. They exhibit two charge-separated transient states, CS1 and CS2, that appear in sequence. CS1 has a short lifetime (542 fs), and the D 1 moiety on CS1 is in the radical cation state with an absorption maximum (λ max ) at 889 nm. CS1 then converts into CS2 (λ max , 1105 nm) through an ICT between D 1 .+ and D 2 , affording D 1 (1−δ).+ and D 2 δ.+. Compounds 1 c, 1 d, 2 c, and 2 d show protonation-induced intramolecular electron transfer that leads to absorption at λ=700–1300 nm. Owing to the existence of an electron-rich C=C bond on the D 1 moiety and in situ generation of 1O 2 by the pyrazine-fused D 2 moiety, compounds 1 c, 1 d, 2 c, and 2 d display self-sensitized photooxidation in 50 s. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Performance of hole transporting material (HTM) plays a fundamental role in estimating overall efficiency of perovskite solar cell (PSC). Dopant free HTMs with high intrinsic hole mobility and stability have been emerged as a fascinating choice for production of highly efficient and stable PSCs. Here, we report facile synthesis and implementation of a novel tetrathiafulvalene (TTF) derivative as a dopant free HTM for efficient and ambient stable PSC. The PSC based on dopant free TTF HTM shows remarkable photovoltaic efficiency of 15.66% which is one of highest value for any TTF based HTM. Beside efficiency, PSC based on TTF HTM shows only about 16% decline in initial efficiency even after 45 days storage in ambient conditions without any encapsulation which verifies its excellent ambient stability and hydrophobicity. Furthermore, various physical, electrochemical, photovoltaic and optical parameters of TTF HTM are investigated by highly specialized characterization tools. We affirm these results will be helpful for developing novel HTMs for highly efficient and stable PSCs in future.

Buckybowls attract significant attention in chemistry and materials science owing to their unique features related to both geometric and electronic aspects. Doping the π-skeleton of buckybowls with the main group elements results in hetera-buckybowls, and accordingly has a large influence on the chemical and physical properties. This account summarizes our research progress on hetera-buckybowl trichalcogenasumanenes (TCSs), including their synthesis, regioselective oxidations, transformation into various hetero polycycles (chiral π-systems, molecular spoons, etc.), and their application as optoelectronic materials.1 Introduction2 Synthesis of TCSs3 Structural and Electronic Features of TCSs4 Regioselective Oxidation of TCSs4.1 Cleavage of the Edged Benzene Rings4.2 Oxidation of the Thiophene Rings4.3 Transformation of Butoxy Groups into an ortho-Quinone4.4 Intermolecular Charge Transfer4.5 Influence of Chalcogen Atoms on Oxidation Reactions5 Synthesis of Hetero Polycycles from TCSs6 Optoelectronic Properties of TCSs and Their Derivatives7 Conclusion

Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight, flexibility and roll-to-roll fabrication. Nowadays, 18% power conversion efficiency has been achieved in the state-of-the-art organic solar cells. The recent rapid progress in organic solar cells relies on the continuously emerging new materials, device fabrication technologies, and the deep understanding on film morphology, molecular packing and device physics. Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance. The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors. In this review, we focus on those star materials and milestone work, and introduce the molecular structure evolution of the key materials. These key materials include homopolymer donors, D-A copolymer donors, A-D-A small molecule donors, fullerene acceptors and nonfullerene acceptors. At last, we outlook the challenges and very important directions in key materials development.

Past decades have witnessed the rapid development of conjugated polymers because of their promising semiconducting properties and applications in organic field-effect transistors (OFETs). Recent studies have shown that side-chain engineering of conjugated polymers is an efficient strategy to increase semiconducting performance. This Perspective focuses on the side-chain modulation of conjugated polymers and evaluating their effects on the performance of OFETs. The challenges and potential applications of functional high-performance OFETs through side-chain engineering are also discussed.

This study was to explore the diversity of rhizosphere and endophytic microbial communities and the correlation with soil environmental factors of

Buckybowls have unique properties that can be tailored by embedding main-group elements into their π-scaffolds. Herein, a synthetic approach is developed for producing monoazadichalcogenasumanenes (4 a/4 b, 6 a/6 b, 7 a/7 b) derived from sumanene by replacing its three benzylic carbons with one nitrogen and two chalcogen atoms (S for 4 a/4 b, Se for 6 a/6 b, Te for 7 a/7 b). Monoazadichalcogenasumanenes are deeper π-bowls than trichalcogensumanenes as the C-N bond is much shorter than C-X (X=S, Se, Te). The bowl-depth of 4 b (0.95 Å) is greater than that of corannulene (0.85 Å). The nitrogen atom donates electron density to the entire π-system that makes monoazadichalcogenasumanenes electron-rich. They undergo ring reconstruction of chalcogenophene ring via transferring a chalcogen atom from one molecule to another under acidic conditions. The nitrogen and chalcogen atoms play crucial role on this reaction.

An application for dechalcogenization of aryl dichalcogenides via copper catalysis to synthesize aryl chalcogenides is disclosed. This approach is highlighted by the practical conditions, broad sub...

Spirocyclic diketones with chiral all-carbon quaternary stereocenters constructed via a semipinacol rearrangement of vinylogous α-ketol cocatalyzed by a cinchona-based primary amine and Bronsted acids such as N-Boc-phenylglycine can be obtained with good enantiocontrol. Two different catalytic systems including cinchona-based primary amine/N-Boc-L-phenylglycine and cinchona-based primary amine/N-Boc-D-phenylglycine can lead to the same major products but with different enantioselectivities. To uncover the detailed reaction mechanism of the semipinacol rearrangement, the roles of catalysts and the origin of enantioselectivity, quantum mechanical calculations were performed. The reaction pathways investigated show that the reactions proceed via the steps of complexation, nucleophilic addition, dehydration, carbon atom migration, enamine–imine tautomerization, imine hydrolysis, Walden inversion and catalyst regeneration. Analyses of noncovalent interactions and quantum theory of atoms in molecules were employed to elucidate the intermolecular interactions occurring between the catalysts and reactants and their roles. The distortion/interaction models were used to reveal the origin of enantioselectivity by analyzing the transition state in the enantioselectivity-determining step of carbon atom migration. The results show that the cinchona-based primary amine plays a crucial role in determining the enantioselectivity while the Bronsted acid additives influence the enantioselectivity to some extent. It is expected that the results would shed light on the organocatalytic semipinacol rearrangement, the roles of the co-catalytic system and the origin of enantioselectivity.

Organic and organometallic π-conjugated molecules with inherent nonlinear optical (NLO) responses have attracted great interest due to their controllable properties via rational structure modifications. However, most of the state-of-the-art materials such as porphyrins, phthalocyanines, and diacetylenes exhibit NLO responses at visible-light regions. Recently, diketopyrrolopyrrole (DPP) based donor–acceptor (D–A) type π-conjugated copolymers have been found to exhibit NLO responses which can reach up to 1064 nm. However, the design rationality of the structure toward NLO properties is not well understood. Herein, four alternating DPP-based copolymers are constructed by using the electron donors of 2-phenylpyridine for P1, 2-thienylpyridine for P2 and their Pt(II)-incorporated moieties for P1Pt and P2Pt. All copolymers display intense intramolecular charge transfer (ICT) processes, and the ICT absorption can be extended to the near-infrared (NIR) region due to the strong D–A interaction of the π-conjugated backbone. The variation tendency of optical bandgaps estimated from the onset of ICT absorption is P1 (1.60 eV) > P1Pt (1.56 eV) > P2 (1.47 eV) > P2Pt (1.44 eV). Open- and closed-aperture Z-scan experiments disclosed that all copolymers exhibit broadband (532 and 1064 nm) NLO properties due to the synergistic effect of excited state absorption and the ICT process upon excitation of 8 ns as well as 25 ps laser pulses. Pt(II)-incorporation can promote or switch the NLO properties due to the efficient triplet-state absorption introduced by the heavy-atom effect. The improvement of the NLO properties is of the order P1 < P1Pt < P2 < P2Pt, which is consistent with the decreasing trend of the copolymer bandgaps. These results will provide guidelines for the rational design of materials toward broadband NLO responses and advanced applications.

Organic nonlinear optical (NLO) materials have attracted immense scientific interest in various fields. Broadband NLO response extending to near-infrared (NIR) region is extremely important and remains challenging. Herein, two diketopyrrolopyrrole (DPP)-based donor-acceptor (D-A)-type π-conjugated copolymers with and without Pt(II) incorporation are rationally designed and synthesized toward broadband NLO response materials. The broad intramolecular charge transfer (ICT) absorption reaching 1000 nm due to the strong D-A interaction is well demonstrated by photophysical characterizations. The NLO properties of copolymers are studied using Z-scan technology. Owing to their extended π-conjugated D-A systems and near-infrared ICT absorption properties, both copolymers exhibit laser-induced NLO response to nanosecond as well as picosecond laser pulses upon the wavelengths of 532 and 1064 nm. Interestingly, introducing Pt(II) into the copolymer backbone can evidently improve the NLO property or unexpectedly switch the NLO response from saturable absorption to reverse saturable absorption. Meanwhile, both copolymers are successfully employed as optical limiting materials and exhibit broadband optical limiting abilities. Therefore, we present an efficient strategy toward broadband NLO materials, which may significantly facilitate the understanding of organic molecular structure-property relationship and promote their practical application.

Two-dimensional (2D) hybrid perovskites have shown many attractive properties associated with their soft lattices and multiple quantum well structure. Herein, we report the synthesis and characterization of two new multifunctional 2D hybrid perovskites, (PED)CuCl 4 and (BED) 2 CuCl 6 , which show reversible thermochromic behavior, dramatic temperature-dependent conductivity change, and strong ferromagnetism. Upon temperature change, the (PED)CuCl 4 and (BED) 2 CuCl 6 crystals exhibit a reversible color change between yellow and red-brown. The associated structural changes were monitored by in situ temperature-dependent powder X-ray diffraction (PXRD). The (BED) 2 CuCl 6 exhibits superior thermal stability, with a thermochromic working temperature up to 443 K. The conductivity of (BED) 2 CuCl 6 changes over six orders of magnitude upon temperature change. The 2D perovskites exhibit ferromagnetic properties with Curie temperatures around 13 K. © 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

A new type of BODIPY dye, compound 2 which possesses donor-acceptor (D-A) type structure, is synthesized by decorating electron-rich THDTAP unit onto the meso-position of BODIPY. The THDTAP has two chemically active sites (S and N atoms) that are utilized to manipulate the optoelectronic properties. By stepwise oxidation of two S-atoms on THDTAP moiety with m-CPBA, the 2 was converted to 3, trans-4, syn-4, 5, and 6. This transformation results in large influence on optoelectronic properties. The theoretical calculations reveal that the LUMOs of 2–6 are all located on BODIPY core, whereas their HOMOs show the different distributions. The 2 and 3 show the intramolecular charge-transfer (ICT) transition as proved by TD-DFT calculations, red-shifts of absorption and emission bands, and solvatochromism. The ICT process is inhibited in trans-4, syn-4, 5, and 6 due to the high oxidation states of S-atoms on THDTAP moieties. As a result, these four compounds display characteristic fluorescence of BODIPY. The femtosecond transient absorption (fs-TA) spectroscopic study reveals that 2 shows photoinduced hole-transfer (PHT) process in dichloromethane (DCM) solution. Upon acidification and neutralization of N-atom on THDTAP moiety, the ICT/PHT process of 2 in DCM is reversibly manipulated to result in fluorescence ON/OFF of BODIPY core. Moreover, the fluorescence of BODIPY core on 2 can be switched on through electrochemical oxidation of N-atom on THDTAP moiety. The compound 2 is thus a promising fluorometric sensor toward peroxide, acid, and electrochemical stimuli.

Four tetraphenylethylenes (2 a-d) containing an electron-rich 2,3,4,6-tetrahydro-1,6-dithia-3a-azaphenalene (THDTAP) moiety have been synthesized. The 2 a-d show aggregation-induced emission (AIE) with yellowish green photoluminescence (PL) in THF-H2 O (v/v, 1:9) solution and in the solid state. Compounds 2 a-d undergo 1,2-migratory shift in oxidative cyclodehydrogenation reactions to afford the unexpected products 3 a-d which display green PL in CH2 Cl2 solution and are non-emissive in the solid state. The PL intensities of 3 a-d are clearly enhanced in the presence of meta-chloroperoxybenzoic acid (mCPBA) owing to the oxidation of the S-atoms on the THDTAP moiety. In contrast, the PL of 2 a-d in THF-H2 O (v/v, 1:9) solution is quenched by adding mCPBA, ascribable to the oxidation of the C=C bond on the ethylene moiety. It is found that the absorption of 3 a-d is distinctly red-shifted from the UV/Vis region to the NIR region upon acidification, arising from the protonation of the N-atom on the THDTAP moiety. Furthermore, 3 a-d display nonlinear optical response (NLO) and optical limiting (OL) behaviour which is superior to that of the well-known OL material C60 .

Heterasumanenes 4-6 containing chalcogen (S, Se, and Te) and phosphorus atoms have been synthesized in a one-pot reaction from trichalcogenasumanenes 1-3 by replacing one chalcogen atom with a P=S unit. The P=S unit makes 4-6 almost planar and shrinks the HOMO-LUMO gap as compared to 1-3. The bonding between Ag+ and S atom on P=S brings about a distinct change to the optical properties of 4-6; 4 in particular shows a selective fluorescence response toward Ag+ with LOD of 0.21 μm. Compounds 4-6 form complexes with AgNO3 to be (4)2 ⋅AgNO3 , (5)2 ⋅AgNO3 , and (6)2 ⋅(AgNO3 )3 . In complexes, the coordination between Ag+ and P=S is observed, which leads to shrinkage of C-P and C-X (X=S, Se, Te) bond lengths. As a result, 4, 5, and 6 are all bowl-shaped in complexes with bowl-depths reaching to 0.66 A, 0.42 A, and 0.40 A, respectively. There are Ag-Te dative bonds between Ag+ and Te atom on telluorophene in (6)2 ⋅(AgNO3 )3 .

Trichalcogenasumanenes (1–3) are rich in chemistry, as they can be regio-selectively functionalized. Chalcogen atoms (S, Se, and Te) play a pivotal role in determining molecular geometry, optical properties, and reactivity. Herein, new trichalcogenasumanenes (4–9) are synthesized, all with the benzylic carbons on sumanene replaced by two kinds of chalcogen atom. Crystallographic studies show that the molecular geometry varies from bowl-shaped (4 and 6) to planar (9) as the size of the majority chalcogen atom increases from S (4) to Se (6) to Te (9). The optical properties of sulfur-rich (4–5), selenium-rich (6–7), and tellurium-rich (8–9) examples are respectively similar to those of trithia- (1), triselena- (2), and tritellura-sumanenes (3). The chemical activities of 4–7 are evaluated via reactions with Oxone, H2O2, and Br2. It is found that their reactivities are dominated by the heavier chalcogen atom rather than the one in the majority.

Electrostatically enhanced thiourea behaves more efficiently than Schreiner's thiourea in the ring-opening aminolysis of styrene oxide with aniline, and the underlying reasons were uncovered by DFT calculations, the distortion/interaction theory, and NBO and QTAIM analyses. Electrostatically enhanced thiourea combines with a substrate much stronger than Schreiner's thiourea, so it activates the substrate more efficiently and thus lowers the activation energy more significantly, leading to a higher reaction rate and a greater conversion.

Thermal instability is one of the major obstacles for the application of organic devices. We report herein for

Distinguishing structural isomers at the single-molecule level remains a challenge. We report the single-molecule recognition of two diketopyrrolopyrrole containing isomers (SDPP and SPPO) employing the mechanically controllable break junction technique. The single-molecule conductances of the two isomers are indistinguishable under normal conditions. However, reversible protonation and deprotonation of the SPPO in molecular junction result in more than 1 order of magnitude conductance change, which dramatically enhances the conductance difference between the two isomers. Theoretical study reveals that the dramatic conductance switching is due to reversible quantum interference effect. It is suggested that combination of stimuli-response and quantum interference can be an efficient strategy to enhance isomer recognition and conductance switching in single-molecule junctions.

Two flanking benzene rings on trichalcogenasumanenes (1a/1b) were opened upon oxidation, and the successive ring reconstruction afforded donor-acceptor type polycycles containing diimide units (3a/3b). 3a and 3b show excellent optical-limiting properties superior to C60.

Chiral bisoxazoline can catalyze the decarboxylative aldol reactions between β-carbonyl acids and trifluoroacetaldehyde hemiacetals as well as trifluoroacetaldehyde but with quite different enantioselectivities, in which the reaction involving trifluoroacetaldehyde hemiacetal results in excellent enantioselectivity (95% ee) while that involving trifluoroacetaldehyde results in poor enantioselectivity (28% ee). To uncover their differences, quantum mechanical calculations together with theoretical methods of global reactivity indexes, QTAIM, NCI and distortion/interaction models were applied to these two reactions; the reaction mechanism, the origin of enantioselectivity and the role of bisoxazoline were investigated in detail. For the reaction with 95% ee, it undergoes the processes of decomposition of trifluoroacetaldehyde hemiacetal, nucleophilic addition, decarboxylation and enol–keto tautomerization of the product, and the nucleophilic addition is the rate- and stereo-determining step. Both the distortion energy and weak intermolecular interactions are responsible for the enantioselectivity. For the reaction with 28% ee, it goes through the processes of nucleophilic addition, decarboxylation and enol–keto tautomerization of the product. Chiral bisoxazoline plays a crucial role in increasing the nucleophilicity of β-carbonyl acid in the reaction leading to 95% ee, while such a role is not observed in the reaction resulting in 28% ee. The calculated ee values are in good agreement with the experimental results. The results shown here will provide valuable insights into the understanding of these types of reactions, the design of highly efficient organocatalysts, and related asymmetric reactions.

A series of hetero polycycles (5a-6b) are created through the hybridization of the bowl-shaped trichalcogenasumanenes and planar triazacoronene. Among them, 6a and 6b bear the 2,2′-bipyridine (bpy) ligand in the lateral direction. The crystallographic analyses show that 6a and 6b possess planar cores, whereas they are driven to bowl-shaped (bowl depth, 0.38–0.50 A) via chelation of Zn2+ by the bpy unit at room temperature (RT). This is caused by the formation of a five-membered ring upon coordination with Zn2+. The coordination of Zn2+ also brings distinct variation of the optical properties, i.e., the crystals of 6a and 6a[ZnCl2] respectively show green and red fluorescence. Moreover, 5a-6b exhibit a reversible color change and a fluorescence OFF/ON response upon acidification and neutralization. Owing to the multiple protonation process, 6a and 6b display a gradient color change from yellow to magenta, violet, and blue as the amount of acid increases. These new hetero polycycles (5a-6b) have potential applications as chemosensors and/or switches.

The C3v-symmetric hetera buckybowl trichalcogenasumanenes have attracted recent interest due to their unique features in chemical and optoelectronic aspects. To gain a nonlinear optical (NLO) response, the electron-withdrawing unit pyrazine was introduced onto tricalcogenasumanenes to give the pyrazine-fused trithiasumanene (1) and triselenasumanene (2) as reported herein. Compounds 1 and 2 exhibit typical NLO properties which are verified using open-aperture Z-scan technology under a 532 nm nanosecond laser pulse. It is found that the NLO performance of these two molecules is much better than the state-of-the-art NLO material C60. The time-resolved transient absorption clearly verified that the NLO properties of 1 and 2 originate from the reverse saturable absorption (RSA) of the triplet excited-state. Owing to their remarkable NLO performance, 1 and 2 are further employed as optical power limiting (OPL) materials. Compounds 1 and 2 exhibit OPL behavior with a limiting threshold of 1.78 J cm−2 and 2.43 J cm−2, respectively; this performance is better than that of C60 (12.85 J cm−2). This work indicates that the sumanene derivatives are promising candidates for NLO and OPL materials.